<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT    MIT License
 * @link    http://codeigniter.com
 * @since    Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Typography Class
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Helpers
 * @author        EllisLab Dev Team
 * @link        http://codeigniter.com/user_guide/libraries/typography.html
 */
class CI_Typography {

    /**
     * Block level elements that should not be wrapped inside <p> tags
     *
     * @var string
     */
    public $block_elements = 'address|blockquote|div|dl|fieldset|form|h\d|hr|noscript|object|ol|p|pre|script|table|ul';

    /**
     * Elements that should not have <p> and <br /> tags within them.
     *
     * @var string
     */
    public $skip_elements    = 'p|pre|ol|ul|dl|object|table|h\d';

    /**
     * Tags we want the parser to completely ignore when splitting the string.
     *
     * @var string
     */
    public $inline_elements = 'a|abbr|acronym|b|bdo|big|br|button|cite|code|del|dfn|em|i|img|ins|input|label|map|kbd|q|samp|select|small|span|strong|sub|sup|textarea|tt|var';

    /**
     * array of block level elements that require inner content to be within another block level element
     *
     * @var array
     */
    public $inner_block_required = array('blockquote');

    /**
     * the last block element parsed
     *
     * @var string
     */
    public $last_block_element = '';

    /**
     * whether or not to protect quotes within { curly braces }
     *
     * @var bool
     */
    public $protect_braced_quotes = FALSE;

    /**
     * Auto Typography
     *
     * This function converts text, making it typographically correct:
     *    - Converts double spaces into paragraphs.
     *    - Converts single line breaks into <br /> tags
     *    - Converts single and double quotes into correctly facing curly quote entities.
     *    - Converts three dots into ellipsis.
     *    - Converts double dashes into em-dashes.
     *  - Converts two spaces into entities
     *
     * @param    string
     * @param    bool    whether to reduce more then two consecutive newlines to two
     * @return    string
     */
    public function auto_typography($str, $reduce_linebreaks = FALSE)
    {
        if ($str === '')
        {
            return '';
        }

        // Standardize Newlines to make matching easier
        if (strpos($str, "\r") !== FALSE)
        {
            $str = str_replace(array("\r\n", "\r"), "\n", $str);
        }

        // Reduce line breaks.  If there are more than two consecutive linebreaks
        // we'll compress them down to a maximum of two since there's no benefit to more.
        if ($reduce_linebreaks === TRUE)
        {
            $str = preg_replace("/\n\n+/", "\n\n", $str);
        }

        // HTML comment tags don't conform to patterns of normal tags, so pull them out separately, only if needed
        $html_comments = array();
        if (strpos($str, '<!--') !== FALSE && preg_match_all('#(<!\-\-.*?\-\->)#s', $str, $matches))
        {
            for ($i = 0, $total = count($matches[0]); $i < $total; $i++)
            {
                $html_comments[] = $matches[0][$i];
                $str = str_replace($matches[0][$i], '{@HC'.$i.'}', $str);
            }
        }

        // match and yank <pre> tags if they exist.  It's cheaper to do this separately since most content will
        // not contain <pre> tags, and it keeps the PCRE patterns below simpler and faster
        if (strpos($str, '<pre') !== FALSE)
        {
            $str = preg_replace_callback('#<pre.*?>.*?</pre>#si', array($this, '_protect_characters'), $str);
        }

        // Convert quotes within tags to temporary markers.
        $str = preg_replace_callback('#<.+?>#si', array($this, '_protect_characters'), $str);

        // Do the same with braces if necessary
        if ($this->protect_braced_quotes === TRUE)
        {
            $str = preg_replace_callback('#\{.+?\}#si', array($this, '_protect_characters'), $str);
        }

        // Convert "ignore" tags to temporary marker.  The parser splits out the string at every tag
        // it encounters.  Certain inline tags, like image tags, links, span tags, etc. will be
        // adversely affected if they are split out so we'll convert the opening bracket < temporarily to: {@TAG}
        $str = preg_replace('#<(/*)('.$this->inline_elements.')([ >])#i', '{@TAG}\\1\\2\\3', $str);

        /* Split the string at every tag. This expression creates an array with this prototype:
         *
         *    [array]
         *    {
         *        [0] = <opening tag>
         *        [1] = Content...
         *        [2] = <closing tag>
         *        Etc...
         *    }
         */
        $chunks = preg_split('/(<(?:[^<>]+(?:"[^"]*"|\'[^\']*\')?)+>)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE|PREG_SPLIT_NO_EMPTY);

        // Build our finalized string.  We cycle through the array, skipping tags, and processing the contained text
        $str = '';
        $process = TRUE;

        for ($i = 0, $c = count($chunks) - 1; $i <= $c; $i++)
        {
            // Are we dealing with a tag? If so, we'll skip the processing for this cycle.
            // Well also set the "process" flag which allows us to skip <pre> tags and a few other things.
            if (preg_match('#<(/*)('.$this->block_elements.').*?>#', $chunks[$i], $match))
            {
                if (preg_match('#'.$this->skip_elements.'#', $match[2]))
                {
                    $process = ($match[1] === '/');
                }

                if ($match[1] === '')
                {
                    $this->last_block_element = $match[2];
                }

                $str .= $chunks[$i];
                continue;
            }

            if ($process === FALSE)
            {
                $str .= $chunks[$i];
                continue;
            }

            //  Force a newline to make sure end tags get processed by _format_newlines()
            if ($i === $c)
            {
                $chunks[$i] .= "\n";
            }

            //  Convert Newlines into <p> and <br /> tags
            $str .= $this->_format_newlines($chunks[$i]);
        }

        // No opening block level tag? Add it if needed.
        if ( ! preg_match('/^\s*<(?:'.$this->block_elements.')/i', $str))
        {
            $str = preg_replace('/^(.*?)<('.$this->block_elements.')/i', '<p>$1</p><$2', $str);
        }

        // Convert quotes, elipsis, em-dashes, non-breaking spaces, and ampersands
        $str = $this->format_characters($str);

        // restore HTML comments
        for ($i = 0, $total = count($html_comments); $i < $total; $i++)
        {
            // remove surrounding paragraph tags, but only if there's an opening paragraph tag
            // otherwise HTML comments at the ends of paragraphs will have the closing tag removed
            // if '<p>{@HC1}' then replace <p>{@HC1}</p> with the comment, else replace only {@HC1} with the comment
            $str = preg_replace('#(?(?=<p>\{@HC'.$i.'\})<p>\{@HC'.$i.'\}(\s*</p>)|\{@HC'.$i.'\})#s', $html_comments[$i], $str);
        }

        // Final clean up
        $table = array(

                        // If the user submitted their own paragraph tags within the text
                        // we will retain them instead of using our tags.
                        '/(<p[^>*?]>)<p>/'    => '$1', // <?php BBEdit syntax coloring bug fix

                        // Reduce multiple instances of opening/closing paragraph tags to a single one
                        '#(</p>)+#'            => '</p>',
                        '/(<p>\W*<p>)+/'    => '<p>',

                        // Clean up stray paragraph tags that appear before block level elements
                        '#<p></p><('.$this->block_elements.')#'    => '<$1',

                        // Clean up stray non-breaking spaces preceeding block elements
                        '#(&nbsp;\s*)+<('.$this->block_elements.')#'    => '  <$2',

                        // Replace the temporary markers we added earlier
                        '/\{@TAG\}/'        => '<',
                        '/\{@DQ\}/'            => '"',
                        '/\{@SQ\}/'            => "'",
                        '/\{@DD\}/'            => '--',
                        '/\{@NBS\}/'        => '  ',

                        // An unintended consequence of the _format_newlines function is that
                        // some of the newlines get truncated, resulting in <p> tags
                        // starting immediately after <block> tags on the same line.
                        // This forces a newline after such occurrences, which looks much nicer.
                        "/><p>\n/"            => ">\n<p>",

                        // Similarly, there might be cases where a closing </block> will follow
                        // a closing </p> tag, so we'll correct it by adding a newline in between
                        '#</p></#'            => "</p>\n</"
                        );

        // Do we need to reduce empty lines?
        if ($reduce_linebreaks === TRUE)
        {
            $table['#<p>\n*</p>#'] = '';
        }
        else
        {
            // If we have empty paragraph tags we add a non-breaking space
            // otherwise most browsers won't treat them as true paragraphs
            $table['#<p></p>#'] = '<p>&nbsp;</p>';
        }

        return preg_replace(array_keys($table), $table, $str);

    }

    // --------------------------------------------------------------------

    /**
     * Format Characters
     *
     * This function mainly converts double and single quotes
     * to curly entities, but it also converts em-dashes,
     * double spaces, and ampersands
     *
     * @param    string
     * @return    string
     */
    public function format_characters($str)
    {
        static $table;

        if ( ! isset($table))
        {
            $table = array(
                            // nested smart quotes, opening and closing
                            // note that rules for grammar (English) allow only for two levels deep
                            // and that single quotes are _supposed_ to always be on the outside
                            // but we'll accommodate both
                            // Note that in all cases, whitespace is the primary determining factor
                            // on which direction to curl, with non-word characters like punctuation
                            // being a secondary factor only after whitespace is addressed.
                            '/\'"(\s|$)/'                    => '&#8217;&#8221;$1',
                            '/(^|\s|<p>)\'"/'                => '$1&#8216;&#8220;',
                            '/\'"(\W)/'                        => '&#8217;&#8221;$1',
                            '/(\W)\'"/'                        => '$1&#8216;&#8220;',
                            '/"\'(\s|$)/'                    => '&#8221;&#8217;$1',
                            '/(^|\s|<p>)"\'/'                => '$1&#8220;&#8216;',
                            '/"\'(\W)/'                        => '&#8221;&#8217;$1',
                            '/(\W)"\'/'                        => '$1&#8220;&#8216;',

                            // single quote smart quotes
                            '/\'(\s|$)/'                    => '&#8217;$1',
                            '/(^|\s|<p>)\'/'                => '$1&#8216;',
                            '/\'(\W)/'                        => '&#8217;$1',
                            '/(\W)\'/'                        => '$1&#8216;',

                            // double quote smart quotes
                            '/"(\s|$)/'                        => '&#8221;$1',
                            '/(^|\s|<p>)"/'                    => '$1&#8220;',
                            '/"(\W)/'                        => '&#8221;$1',
                            '/(\W)"/'                        => '$1&#8220;',

                            // apostrophes
                            "/(\w)'(\w)/"                    => '$1&#8217;$2',

                            // Em dash and ellipses dots
                            '/\s?\-\-\s?/'                    => '&#8212;',
                            '/(\w)\.{3}/'                    => '$1&#8230;',

                            // double space after sentences
                            '/(\W)  /'                        => '$1&nbsp; ',

                            // ampersands, if not a character entity
                            '/&(?!#?[a-zA-Z0-9]{2,};)/'        => '&amp;'
                        );
        }

        return preg_replace(array_keys($table), $table, $str);
    }

    // --------------------------------------------------------------------

    /**
     * Format Newlines
     *
     * Converts newline characters into either <p> tags or <br />
     *
     * @param    string
     * @return    string
     */
    protected function _format_newlines($str)
    {
        if ($str === '' OR (strpos($str, "\n") === FALSE && ! in_array($this->last_block_element, $this->inner_block_required)))
        {
            return $str;
        }

        // Convert two consecutive newlines to paragraphs
        $str = str_replace("\n\n", "</p>\n\n<p>", $str);

        // Convert single spaces to <br /> tags
        $str = preg_replace("/([^\n])(\n)([^\n])/", '\\1<br />\\2\\3', $str);

        // Wrap the whole enchilada in enclosing paragraphs
        if ($str !== "\n")
        {
            // We trim off the right-side new line so that the closing </p> tag
            // will be positioned immediately following the string, matching
            // the behavior of the opening <p> tag
            $str =  '<p>'.rtrim($str).'</p>';
        }

        // Remove empty paragraphs if they are on the first line, as this
        // is a potential unintended consequence of the previous code
        return preg_replace('/<p><\/p>(.*)/', '\\1', $str, 1);
    }

    // ------------------------------------------------------------------------

    /**
     * Protect Characters
     *
     * Protects special characters from being formatted later
     * We don't want quotes converted within tags so we'll temporarily convert them to {@DQ} and {@SQ}
     * and we don't want double dashes converted to emdash entities, so they are marked with {@DD}
     * likewise double spaces are converted to {@NBS} to prevent entity conversion
     *
     * @param    array
     * @return    string
     */
    protected function _protect_characters($match)
    {
        return str_replace(array("'",'"','--','  '), array('{@SQ}', '{@DQ}', '{@DD}', '{@NBS}'), $match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Convert newlines to HTML line breaks except within PRE tags
     *
     * @param    string
     * @return    string
     */
    public function nl2br_except_pre($str)
    {
        $newstr = '';
        for ($ex = explode('pre>', $str), $ct = count($ex), $i = 0; $i < $ct; $i++)
        {
            $newstr .= (($i % 2) === 0) ? nl2br($ex[$i]) : $ex[$i];
            if ($ct - 1 !== $i)
            {
                $newstr .= 'pre>';
            }
        }

        return $newstr;
    }

}
